In general, when the pneumatic tire is punctured during the running, the vehicle is moved (evacuated) at a decelerated rate up to a safe place such as a tire repairing factory or the like, which is located in a relatively short range from the punctured position (concretely, about 50 km at maximum, usually about 10-20 km), and then the punctured tire is subjected to a repairing at this place.
In the puncture of the pneumatic tire, however, the support of load through an internal pressure is lost and also the tire itself has not a reinforcing structure capable of supporting the load, so that the tire is largely deformed at a crushed state and hence the steering performance is apt to be violently lowered, and it is assumed that when the tire is particularly punctured during the running at a high speed, the driver encounters into a very risky status.
Further, the punctured tire is forced into the running at a large crushed state under loading because the deformation quantity of the tire in the radial direction at the punctured state becomes generally about 80% of a section height of the tire at a normal state. Even if the vehicle is unavoidably moved up to the relatively short-range safe place after the puncture, a sidewall portion of the tire is strongly deformed between a rim flange and a road surface in the unavoidable running, and particularly rubber parts inside the sidewall portion of the tire are repeatedly rubbed with each other, so that there is a fear that the inner face of the tire is damaged but also there is a possibility that the outer face of the sidewall portion or further the rim flange or the like are damaged.
In the conventional pneumatic tire, therefore, it is possible to largely damage the tire due to the unavoidable running at the punctured state. Once the tire is damaged, there is a possibility that the damaged tire can not be turned to an original state even by repairing.
Furthermore, JP-A-2003-63221, JP-A-2003-159918 and JP-A-2003-165315 disclose an alarm device wherein the occurrence of puncture during the running of the tire is detected and the detected signal is informed to the driver. In addition, JP-A-9-118779, JP-A-2001-212883 and JP-A-2000-103905 disclose a puncture repairing kit (consisting of a sealant sealing the punctured hole and an air filling device feeding air into the inside of the tire) for turning the punctured tire to a normal state before the puncture.
However, there is not yet found a technique of combining the alarm device or the puncture repairing kit with a pneumatic tire having a structure of controlling the damage of the tire produced by the unavoidable running at the punctured state.
On the other hand, there are developed so-called run-flat tires capable of running over a significant distance (concretely, a running distance of about 200-300 km at a speed of 80 km/h without causing troubles in view of the steering performance) even if the tire is punctured. Such a run-flat tire is a special tire dispensing a spare tire to be mounted onto the vehicle. As the run-flat tire, there are mainly mentioned so-called side-reinforcing type run-flat tires wherein the sidewall portion is strengthened with a reinforcing rubber layer (e.g. JP-A-49-20802, JP-A-49-116702 and the like) and so-called core type run-flat tires wherein a metal support or the like is disposed in the inside of the tire (e.g. JP-A-59-26308, JP-A-3-121913 and the like).
However, the side-reinforcing type run-flat tire is mainly developed in order that the running at the run-flat state is enabled by arranging a thick reinforcing rubber on the sidewall portion to increase a bending rigidity of the sidewall portion, so that there is a tendency that when such a tire is generally run at a normal state under an air inflation, the ride comfort and the rim-assembling property are deteriorated as compared with the ordinary pneumatic tire having no reinforcing rubber but also there is a problem that the arrangement of the thick reinforcing rubber brings about the increase of the weight and hence the increase of the rolling resistance. Particularly, in case of a super-low profile run-flat tire having an aspect ratio of not more than 55%, the deterioration of the ride comfort and rim-assembling property becomes conspicuous due to the fact that the height of the sidewall portion becomes low.
On the other hand, when the core type run-flat tire is generally run at the normal state, since the tire and the support arranged therein are maintained at a non-contact state owing to the presence of air filled in tire so as not to substantially develop the function of the support, the ride comfort is substantially equal to that of the ordinary pneumatic tire having no reinforcing rubber. However, the support should be newly arranged in the tire as an additional member, so that the rim-assembling property is deteriorated by the arrangement of the support as compared with the ordinary pneumatic tire and also there is a problem of increasing the weight and hence the rolling resistance.